Race for Religion use to (back in the G&K days) have a follower belief that provided faith from Trading Posts but the current version does not have any belief that does. Assuming you aren't accidentally using the G&Ks version of Race for Religion than it is likely this is 1) caused by another mod or 2) something caused a file in Race for Religion to abort and it didn't change a belief. Are you using other mods and do they change beliefs at all? If so, it is likely that that mod and Race for Religion are clobbering each other (overwriting each other's changes). If you've enabled logging, could you provide your database.log? It may indicate what is happening. (Let me know if you need help finding it). Lastly, if you want to identify exactly what is happening you could get sqlite manager (a plug in for firefox/your browser of choice) and take a look at the "Belief_ImprovementYieldChange" table in the civ 5 debug database after you've enabled all your mods. This will show you exactly which beliefs provide boosts to trading posts.